Outboard motor with speed regulator for DC permanent magnet motor

ABSTRACT

Disclosed herein is an outboard motor comprising a shaft extending vertically under normal operating conditions and including a hollow interior, a lower housing fixedly connected to the shaft and including a hollow interior, an electric motor mounted in the housing hollow interior and including an output shaft, a propeller driven by the output shaft, a transistor electrically connected to the motor and located in spaced relation axially of the output shaft from the adjacent end of the electric motor, and a thermally conductive agent fixedly bonding the transistor to the housing.

RELATED APPLICATIONS

This is a continuation-in-part of Ser. No. 399,609 filed Sept. 21, 1973,and now abandoned.

Reference is hereby made under the provisions of 35 U.S.C. 120 to myearlier applications Ser. No. 399,609 filed Sept. 21, 1973 and nowabandoned and Ser. No. 504,353 filed Sept. 9, 1974 .Iadd.and nowabandoned. .Iaddend.

BACKGROUND OF THE INVENTION

The invention relates generally to outboard motors and more particularlyto outboard motors including electric motors. Still further, theinvention relates to speed control circuits for outboard motors drivenby permanent magnet electric motors.

The invention also relates generally to speed control of direct currentmotors, and more particularly to speed control of permanent magnetdirect current motors. In the past, speed regulation of permanent magnetdirect current motors was often obtained by employment of a relativelybulky and cost, large wattage variable resistor connected in series withthe direct current motor. In operation, variation in the resistance ofthe resistor changes the motor voltage, and hence, changes the motorspeed. It is noted that the current flowing through the motor also flowsthrough the variable resistor.

Attention is directed to the U.S. Ware Pat. No. 3,593,050 issued July13, 1971 and to the U.S. Green Pat. No. 2,975,349 issued Mar. 14, 1961.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, there is provided anoutboard motor comprising a shaft extending vertically under normaloperating conditions and including a hollow interior, means connected tothe shaft for mounting the shaft to a boat hull, a lower housing fixedlyconnected to the shaft and including a hollow interior, an electricmotor mounted in the housing hollow interior and including an outputshaft, a propeller driven by the output shaft, a transistor electricallyconnected to the motor and located in the housing hollow interior inspaced relation axially of the output shaft from the adjacent end of theelectric motor, and a thermally conductive means fixedly bonding thetransistor to the housing.

In accordance with a preferred embodiment of the invention, thethermally conductive means comprises an epoxy cement and the transistoris embedded in the cement with the transistor and the cement being inspaced relation from the adjacent end of the electric motor so asthereby to provide an air space therebetween.

In accordance with another aspect of the invention, there is alsoprovided a speed control circuit comprising a source of direct currenthaving positive and negative terminals, a permanent magnet motorincluding an armature winding electrically connected between thepositive and negative terminals, a first transistor having a collectorand an emitter electrically connected in series with the armaturewinding between the positive and negative terminals, which firsttransistor also includes a base, a second transistor connected inparallel with the first transistor and having a collector and an emitterelectrically connected in series with the armatutre winding between thepositive and negative terminals, which second transistor includes abase, and a potentiometer electrically connected to the negativeterminal and directly electrically connected to the bases of the firstand second transistors.

In further accordance with a preferred embodiment of the invention, thetransistors are preferably germanium transistors. Direct electricalconnection of the transistor bases to the potentiometer affordscontinuous current flow at a steady level through the motor andtransistors at any given motor loading and potentiometer setting.

Thus, speed regulation of a permanent magnet direct current motor isprovided by controlling the bias of the voltage drop between thetransistor emitter and collector by reason of operation of thepotentiometer which passes a relatively small current, but isnevertheless operative to control the relatively large current whichpasses through the direct current motor and through the transistor.

In accordance with still another aspect of the invention, there isprovided a speed control circuit for a permanent magnet, direct currentmotor comprising a source of direct current having positive and negativeterminals, a permanent magnet motor including an armature windingelectrically connected between the positive and negative terminals, atransistor having a collector and an emitter electrically connected inseries with the armature winding between the positive and negativeterminals, which transistor also includes a base, a resistor connectedbetween the emitter and the base, and a potentiometer electricallyconnected between the base and the negative terminal.

One of the principal features of the invention is the provision of anoutboard motor which includes a permanent magnet electric motor and aspeed control circuit including one or more transistors located in anunderwater housing in spaced relation from the electric motor andseparated from the electric motor by a partition extending in spacedrelation from the transistors and between the transistors and theelectric motor.

Still another of the principal features of the invention is theprovision of an outboard motor which includes a permanent magnetelectric motor and a speed control circuit including one or moretransistors located in an underwater housing in spaced relation axiallyfrom one end of the electric motor and separated from the motor by anair space.

Another of the principal features of the invention is to regulate thespeed of a permanent magnet, direct current motor by controlling acurrent which is relatively small as compared to the current flowingthrough the motor.

Still another of the principal features of the invention is theprovision of a speed control for a permanent magnet, direct currentmotor in which motor hum is reduced.

Still another of the principal features of the invention is theprovision of a speed control circuit including a pair of transistorsarranged in parallel.

Still another of the principal features of the invention is theprovision of a speed control for a permanent magnet, direct currentmotor which is of relatively simple construction, which is relativelysmall in size, which is economical to construct, and which will providereliable service over a large and useful life.

Other features and advantages of the embodiments of the invention willbecome known by reference to the following drawings, generaldescription, and claims.

THE DRAWINGS

FIG. 1 is a fragmentary side elevational view, partially broken away andin section, of an outboard motor which embodies a permanent magnetdirect current motor and which incorporates various of the features ofthe invention.

FIG. 2 is a wiring diagram of a speed control circuit for a permanentmagnet, direct current motor, which circuit embodies various of thefeatures of the invention and can be incorporated in the outboard motorshown in FIG. 1.

FIG. 3 is a wiring diagram of a second embodiment of a speed controlcircuit for a permanent magnet, direct current motor, which circuitembodies various of the features of the invention and can beincorporated in the outboard motor shown in FIG. 1.

FIG. 4 is a wiring diagram of a third embodiment of a speed controlcircuit for a permanent magnet, direct current motor, which circuitembodies various of the features of the invention and can beincorporated in the outboard motor shown in FIG. 1.

FIG. 5 is a wiring diagram of a fourth embodiment of a speed controlcircuit for a permanent magnet, direct current motor, which circuitembodies various of the features of the invention and can beincorporated in the outboard motor shown in FIG. 1.

FIG. 6 is a wiring diagram of a fifth embodiment of a speed controlcircuit for a permanent magnet, direct current motor, which circuitembodies various of the features of the invention and can beincorporated in the outboard motor shown in FIG. 1.

FIG. 7 is a wiring diagram of a sixth embodiment of a speed controlcircuit for a permanent magnet, direct current motor, which circuitembodies various of the features of the invention and can beincorporated in the outboard motor shown in FIG. 1.

Before explaining the embodiments of the invention in detail, it is tobe understood that the invention is not limited in its application tothe details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments and of being practiced andcarried out in various ways. Also it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

GENERAL DESCRIPTION

Shown in FIG. 1 of the drawings is an outboard motor 11 which includes ashaft 13 having a hollow interior 15 and which is carried for steeringmovement about an axis extending lengthwise of the shaft 13 under normaloperating conditions and for tilting movement about a horiozontal axisby any suitable means such as disclosed in the U.S. ShimanckasApplication, Ser. No. 381,602 filed July 23, 1973 and now U.S. Pat. No.3,870,258, and incorporated herein by reference.

At its lower end, the shaft 13 is suitably connected, as by a screwthread connection or otherwise, to an underwater housing 17 whichincludes an adapter housing member 21 having a rearwardly open cavity orrecess 23 communicating with the hollow interior 15 of the shaft 13. Therecess 23 includes a rearwardly open counterbore 25 and the adapterhousing member 21 includes a rearwardly facing surface 27 extending fromthe outer or rearward end of the counterbore 25.

Connected to the rearward surface 27 of the adapter housing member 21 isa motor housing member 31 including a hollow interior cavity or chamber32 containing and supporting a direct current motor 33 which,preferably, is a permanent magnet motor and which includes an armaturewinding 35. The motor 33 also includes an output shaft 37 which canextend rearwardly from the motor housing member 31 and can have apropeller 39 mounted thereon for rotation in common with the outputshaft 37. The motor housing member 31 also includes, forwardly of theelectric motor 33, a transverse wall or partition 41 which separates therecess 23 from the cavity 32. The motor housing member 31 can beconnected to the adapter housing member 21 in any suitable fashion, and,in the disclosed construction, is connected by a plurality of bolts 43which extend through portions of the adapter housing member 21 and arethreaded into the motor housing member 31.

The counterbore 25 serves as a pilot and, preferably, the motor housingmember 31 includes a pilot projection 45 which is received in the pilotcounterbore 25 to properly locate the motor housing member 31 relativeto the adapter housing member 21. A seal 47 in the form of an O-ring isalso provided to prevent entry of water into the adapter recess orcavity 23 or into the chamber or cavity 32 of the motor housing member31. Contained in the adapter recess or cavity 23 is a portion of a motorcontrol circuit such as shown in FIGS. 2 through 7.

Shown in FIG. 2 is a wiring diagram of one embodiment of a speed controlcircuit 111 for the permanent magnet, direct current motor 33 includingthe armature winding 35. The armature winding 35 is connected to anysuitable source of a direct current, as for instance a battery 117,including a positive terminal 119 and a negative terminal 121 which ispreferably grounded, as indicated at 123. As used herein, negativeterminal and ground are interchangeable.

Control of the speed of the direct current motor 33 is provided by atransistor 131 having a collector 133 and an emitter 135 connectedbetween the positive and negative terminals 119 and 121, respectively,in series with the armature winding 35. Preferably, the transistor 131is of the germanium type. In the specifically disclosed construction,the emitter 135 is electrically connected to the armature winding 35 andthe collector 133 is electrically connected to the negative terminal 121of the battery 117 or other direct current source.

Means are provided to adjust the bias or conductivity of the transistor131, and, in this regard, the transistor 131 includes a base 141 whichis electrically connected to a potentiometer 143 which, in turn, isconnected to the negative terminal 121 of the battery 117 or otherdirect current source. Alternatively, the potentiometer 143 could bedirectly grounded. Accordingly, variation in the setting of thepotentiometer 143 serves to vary the bias or impedance of the transistor131 and thereby to control the speed of the motor 33 under a given load.

Because the potentiometer 143 is directly connected to the transistorbase 141 without intervening components, the potentiometer 143 therebydirectly and immediately controls the bias of the transistor 131 and thetransistor accordingly conducts continuously and at a steady rate for agiven potentiometer setting and under constant motor load conditions.Furthermore, the current which is directly controlled by thepotentiometer 143 is relatively small as compared to the current whichflows through the motor 33 and to the collector 133 from the emitter 135of the transistor 131.

In addition to the speed control just described, means are provided inthe circuit 111 for controlling energizing of or electrical connectionof the motor 33 to the direct current source 117, including a masterswitch 151 and a motor control switch 153. In the illustrated circuit111, the master switch 151 is connected to the positive terminal 119 ofthe battery 117 or other direct current source, and the motor controlswitch 153 is connected in series between the master switch 151 and thearmature winding 115. Both switches 151 and 153 must be closed to obtainmotor operation, and opening of either switch prevents motor operation.

Means are also provided for determining the availability of directcurrent from the battery 117 or other source. In the illustratedconstruction, such means comprises an indicating sub-circuit 161 whichis connected to the master switch 151 in common with the connection ofthe motor control switch 153, and which includes an indicator in theform of a lamp 163 which is also connected to ground 123 but couldalternatively be connected to the negative terminal 121 of the battery117 or other direct current source. Accordingly, when there is energyavailable at the battery 117 and when the master switch 151 is closed,the lamp 163 will light, independently of the open or closed position ofthe motor control switch 153, to thereby indicate such availability ofelectrical energy.

In the event the current controlling capacity of the transistor 131 isinsufficient to afford full range speed control of the motor 33, one ormore additional transistors can be connected in parallel with thetransistor 131, as shown in the circuit 211 illustrated in FIG. 3.Specifically, the circuit 211 is substantially identical to the circuit111 shown in FIG. 2 except there is additionally provided a secondtransistor 231 including an emitter 235 connected to the armaturewinding 35 in common with connection of the emitter 135, a collector 233connected to the negative terminal 121 in common with the collector 133,and a base 241 connected directly to the potentiometer 143 in commonwith the base 141. If desired, two separate and independently adjustablepotentiometers, one for each transistor base, could be employed.

Shown in FIG. 4 is still another circuit 311 in accordance with theinvention in which a transistor 331 is located in series with thearmature winding 35 between the armature winding 35 and the positiveterminal 119. In FIG. 4, the transistor emitter 335 is connected to thepositive terminal 119, the collector 333 is connected to the armaturewinding 35, and the base 341 is connected to the potentiometer 143.Otherwise, and except for omission of the transistor 131, theconstruction shown in FIG. 4 is the same as that shown in FIG. 2.

Shown in FIG. 5 is another control circuit 611 which is identical to thecontrol circuit 111 shown in FIG. 2 except that the lead 161 extendingfrom the light 163 is connected between the switch 153 and the motor 33so that the light 163 will be energized to indicate motor operation ascompared to the availability of battery power as provided in the circuit111 shown in FIG. 2.

In addition, the circuit 611 differs from the circuit 111 by addition ofa resistor 175 which is connected between the emitter 135 and thepotentiometer 143 and which provides stability in the biasing of thetransister 131. As shown, the resistor 175 can also be considered asbeing connected between the emitter 135 and the base 141.

Shown in FIG. 6 is another control circuit 711 which is identical to thecircuit 211 shown in FIG. 3 except that the light 163 is connected inthe same manner as in the circuit 611 and except for addition of theresistor 175 which is arranged in the same general manner as in thecircuit 611. The resistor 175 serves to provide stability in the biasingof both transistors 131 and 231.

Shown in FIG. 7 is still another control circuit 811 which is identicalto the control circuit 511 shown in FIG. 4 except that a resistor 175 isconnected between the emitter 335 and the potentiometer 143 in order toprovide stability in the biasing of the resistor. The resistor 175 couldalso be described as extending between the emitter 335 and the base 341.If desired, the light 163 provided in the circuit 811 could be connectedas in the circuits 611 and 711 shown respectively in FIGS. 5 and 6.

The transistors 131, 231 and 331 are preferably located in the recess orcavity 23 in the housing adapter member 21 and are fixed therein bybeing embedded in a thermally conductive agent, such as an epoxy cement,which serves to bond the transistors 131, 231 and 331 to the adapterhousing member 21, while at the same time, providing for high heattransfer from the transistors 131, 231 and 331 to the adapter housingmember 21 and while also electrically insulating the transistors 131,231 and 331 from the housing adapter member 21. It is noted especiallythat the heat generated by the transistors 131, 231 and 331 isdissipated to the water through the adapter housing member 21independently of the motor housing member 31 and that the transistors131, 231 and 331 are spaced from the partition 41 provided by the motorhousing member 31 and from the motor 33 located on the other side of thepartition 41 by an air space or void 49 which also acts to thermallyinsulate the motor 33 from the heat generated by the transistors 131,231 and 331.

The transistors 131, 231 and 331 are connected to the armature winding35 by a lead 160 which extends through the partition 41 in an aperture(not shown) which is sealed by a grommet (not shown) or epoxy cement, orotherwise.

When employing the circuits disclosed in the drawings, a relativelysmall current flowing through the potentiometer 143 serves to control amuch larger current flowing through the motor 33 and to the collectorfrom the emitter of the controlling transistor, whereby considerableeconomies in cost and size can be achieved as compared with use ofrelatively large wattage, variable resistors for directly controllingmotor speeds.

In operation, the master switch 151 and motor control switch 153 areboth closed to supply power to the motor. Instantaneously, the motorbegins running and current passes through the motor 33 and from theemitter to the collector. The speed of the motor 33 is determined by thesetting of the potentiometer 143 and as the potentiometer is varied, thetransistor operating point is changed, thereby changing the bias orimpedance of the transistor and hence the collector-emitter voltage isincreased or decreased. Accordingly, the motor voltage is increased ordecreased, respectively, so as to provide regulation of motor speed.When the potentiometer 143 is completely shorted out, i.e., provides noresistance, the resistance of the armature winding 35 limits the bias orvoltage drop between the emitter and collector of the transistor.

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:
 1. An outboard motor comprising a shaft extendingvertically under normal operating conditions and adapted to be connectedto a boat hull, said shaft including a hollow interior, a lower housingfixedly connected to said shaft and including a hollow interiorcommunicating with said hollow interior of said shaft, an electric motormounted in said housing hollow interior and including an output shaftincluding a first .[.and.]. .Iadd.end .Iaddend.extending exteriorly ofsaid lower housing and a second end terminating within said hollowinterior of said lower housing, a propeller mounted on said first end ofsaid output shaft, a transistor electrically connected to said motor andlocated in said housing hollow interior in axially spaced relation fromsaid output shaft, and a thermally conductive means fixedly bonding saidtransistor to said housing.
 2. An outboard motor in accordance withclaim 1 wherein said thermally conductive means comprises an epoxycement and wherein said transistor is embedded in said cement with saidtransistor and said cement being in axially spaced relation from saidsecond end of said output shaft so as thereby to provide an air spacebetween said epoxy cement and said electric motor.
 3. An outboard motorin accordance with claim 1 wherein said hollow interior includes firstand second chambers separated by a partition, wherein said electricmotor is mounted in said first housing chamber, and said transistor islocated in said second housing chamber.
 4. An outboard motor inaccordance with claim 3 wherein said lower housing includes an adapterhousing member including said second chamber and a motor housing memberconnected to said adaptor housing member and including said firstchamber.
 5. An outboard motor in accordance with claim 3 wherein saidsecond chamber in said .[.adapter.]. housing is closed by saidpartition.
 6. An outboard motor in accordance with claim 3 wherein saidthermally conductive means comprises an epoxy cement and wherein saidtransistor is embedded in said cement with said transistor and saidcement being in spaced relation from said partition so as thereby toprovide an air space therebetween.
 7. An outboard motor in accordancewith claim 1 wherein said motor is a permanent magnet motor including anarmature winding adapted to be electrically connected between thepositive and negative terminals of a source of direct current, whereinsaid transistor includes a collector and an emitter electricallyconnected in series with said armature winding between the positive andnegative terminals, said transistor also including a base, and furtherincluding a second transistor connected in parallel with said firstmentioned transistor and having a collector and an emitter electricallyconnected in series with said armature winding between the positive andnegative terminals, said second transistor including a base, and furtherincluding a potentiometer electrically connected to the negativeterminal and directly electrically connected to said bases of said firstand second transistors.
 8. An outboard motor in accordance with claim 7wherein said transistors are germanium transistors.
 9. An outboard motorin accordance with claim 7 wherein said emitter-base current path isthrough said armature winding.
 10. An outboard motor in accordance withclaim 7 and further including a master switch and a control switchelectrically connected in series between said positive terminal and saidwinding and an indicator electrically connected between said master andcontrol swtiches and additionally electrically connected to saidnegative terminal.
 11. An outboard motor in accordance with claim 7 andfurther including a master switch electrically connected to saidpositive terminal, a control switch electrically connected between saidmaster switch and said winding, and an indicator electrically connectedbetween said control switch and said winding and additionallyelectrically connected to said negative terminal.
 12. An outboard motorin accordance with claim 7 and further including a resistor connectedbetween said winding and said potentiometer.
 13. An outboard motor inaccordance with claim 1 wherein said motor is a permanent magnet motorincluding an armature winding adapted to be electrically connected tothe positive terminal of a source of direct current, wherein said firstmentioned transistor is a germanium transistor and further including asecond germanium transistor arranged in parallel with said firstmentioned transistor, said first and second transistors each having anemitter electrically connected to said armature winding, a collectoradapted to be electrically connected to the negative terminal of thesource of direct current, and a base, and further including apotentiometer directly electrically connected between said bases and thenegative terminal, whereby said first and second transistors affordcontinuous current flow which is substantially uniform during steadyload conditions and at any given potentiometer setting.
 14. An outboardmotor in accordance with claim 13 and further including a master switchand a control switch electrically connected in series between saidpositive terminal and said winding and an indicator electricallyconnected between said master and control switches and additionallyelectrically connected to said negative terminal.
 15. An outboard motorin accordance with claim 13 and further including a master switchelectrically connected to said positive terminal, a control switchelectrically connected between said master switch and said winding, andan indicator electrically connected between said control switch and saidwinding and additionally electrically connected to said negativeterminal.
 16. An outboard motor in accordance with claim 13 and furtherincluding a resistor connected between said winding and saidpotentiometer.
 17. An outboard motor in accordance with claim 1 whereinsaid motor is a direct current motor including an armature windingadapted to be electrically connected between the positive and negativeterminals of a source of direct current and wherein said transistorincludes a collector and an emitter electrically connected in serieswith said armature winding between the positive and negative terminals,and wherein said transistor also includes a base, and further includinga resistor connected between said emitter and said base, and apotentiometer electrically connected between said base and the negativeterminal.
 18. An outboard motor in accordance with claim 17 wherein saidpotentiometer is directly connected to said base and said transistoraffords continuous current flow which is substantially uniform duringsteady load conditions and at any given potentiometer setting.
 19. Anoutboard motor in accordance with claim 17 wherein said transistor is agermanium transistor.
 20. An outboard motor comprising a shaft extendingvertically under normal operating conditions and adapted to be connectedto a boat hull, said shaft including a hollow interior, a lower housingfixedly connected to said shaft and including an adapter member and ahousing member connected to said adapter member and defining an interiorcavity including a partition dividing said cavity into a first chamberlocated in said adapter member and communicating with said hollowinterior of said shaft, and a second chamber located in said housingmember, an electric motor mounted in said second chamber and includingan output shaft including a first end extending exteriorly of saidhousing member and a second end terminating in said second chamber toone side of said partition, a propeller mounted on said first end ofsaid output shaft, a motor control circuit including a transistorelectrically connected to said motor and located in said first chamberon the other side of said partition, and a thermally conductive meansfixedly bonding said transistor to said housing.
 21. An outboard motorin accordance with claim 20 wherein said thermally conductive meanscomprises an epoxy cement and wherein said transistor is embedded insaid cement with said transistor and said cement being in spacedrelation from said partition so as thereby a provide an air spacebetween said epoxy cement and said partition.
 22. An outboard motor inaccordance with claim 20 wherein said first chamber in said adapterhousing is closed by said partition. .Iadd.
 23. An outboard motorcomprising a shaft extending vertically under normal operatingconditions and adapted to be connected to a boat hull, said shaftincluding a hollow interior, a lower housing fixedly connected to saidshaft and including a hollow interior communicating with said hollowinterior of said shaft, an electric motor mounted in said housing hollowinterior and including an output shaft including a first end extendingexteriorly of said lower housing and a second end terminating withinsaid hollow interior of said lower housing, a propeller mounted on saidfirst end of said output shaft, a control circuit for said motorincluding a heat generating electrical component electrically connectedto said motor and located in said housing hollow interior in axiallyspaced relation from said output shaft, and a thermally conductive meansfixedly bonding said heat generating electrical component to saidhousing..Iaddend. .Iadd.
 24. An outboard motor in accordance with claim23 wherein said thermally conductive means comprises an epoxy cement andwherein said heat generating electrical component is embedded in saidcement with said heat generating electrical component and said cementbeing in spaced relation from said second end of said output shaft so asthereby to provide an air space between said epoxy cement and saidelectric motor..Iaddend. .Iadd. An outboard motor in accordance withclaim 23 wherein said hollow interior includes first and second chambersseparated by a partition, wherein said electric motor is mounted in saidfirst housing chamber, and wherein said heat generating electricalcomponent is located in said second housing chamber. .Iaddend. .Iadd.26.An outboard motor in accordance with claim 25 wherein said lower housingincludes an adaptor housing member including said second chamber and amotor housing member connected to said adaptor housing member andincluding said first chamber. .Iaddend. .Iadd.27. An outboard motor inaccordance with claim 26 wherein said first chamber in said housing isclosed by said partition. .Iaddend. .Iadd.28. An outboard motor inaccordance with claim 25 wherein said second chamber in said housing isclosed by said partition. .Iaddend. .Iadd.29. An outboard motorcomprising a shaft extending vertically under normal operatingconditions and adapted to be connected to a boat hull, said shaftincluding a hollow interior, a lower housing fixedly connected to saidshaft and including an adapter member and a housing member connected tosaid adapter member and defining an interior cavity including apartition dividing said cavity into a first chamber located in saidadapter member and communicating with said hollow interior of saidshaft, and a second chamber located in said housing member, an electricmotor mounted in said second chamber and including an output shaftincluding a first end extending exteriorly of said housing member and asecond end terminating in said second chamber to one side of saidpartition, a propeller mounted on said first end of said output shaft, amotor control circuit including a heat generating electrical componentelectrically connected to said motor and located in said first chamberon the other side of said partition, and a thermally conductive meansfixedly bonding said heat generating electrical component to saidhousing. .Iaddend. .Iadd.0. An outboard motor in accordance with claim29 wherein said thermally conductive means comprises an epoxy cement andwherein said heat generating electrical component is embedded in saidcement with said heat generating electrical component and said cementbeing in spaced relation from said partition so as thereby to provide anair space between said epoxy cement and said partition. .Iaddend..Iadd.31. An outboard motor in accordance with claim 29 wherein saidfirst chamber in said housing is closed by said partition..Iaddend.